The ageing response of direct laser deposited metastable β-Ti alloy, Ti-5Al-5Mo-5V-3Cr

The formation of solely beta-phase titanium after direct laser deposition (DLD) of metastable beta-Ti alloy does not provide the desired properties. Hence, we present a study into the ageing response of DLD built Ti-5553 beta-Ti alloy to obtain the bimodal (beta + alpha) microstructure providing improved properties. The results obtained from the heat treatments showed that a unique microstructure with refined intragranular and discontinuous grain boundary alpha-phase can be obtained by directly ageing (using fast heating rate) the as-built samples at the ageing condition (600 degrees C + 0.5 h). This microstructure produced a good balance in mechanical properties (UTS = 1345 +/- 5 MPa and 8 = 11.6 +/- 0.5%). The interparticle spacing between the alpha-phase (d) showed a correlation with microhardness (Hv = 340 + 158/A/d) and yield stress (sigma 0.2 = 870 + 15086/A/d) values for all the aged samples.

Automated summary

This study explores the ageing response of DLD built Ti-5553 beta-Ti alloy, aiming to achieve a bimodal (beta + alpha) microstructure that provides improved properties. Direct ageing at a fast heating rate under specific conditions resulted in a unique microstructure with refined intragranular and discontinuous grain boundary alpha-phase. The interparticle spacing between the alpha-phase showed correlation with microhardness and yield stress values for all aged samples.